PURPOSE: To provide a controller, by which EGR failure determination of equal quality to the conventional one can be carried out while accomplishing a simple, inexpensive, and assured purge failure detecting system, for an internal combustion engine by altering a pressure outlet port, to a pressure sensor.

CONSTITUTION: A controller for an internal combustion engine is provided with an introducing passage 8, which introduces air or an air/fuel mixture to an intake manifold 2 of an engine 1, a control valve 9, which is arranged in the middle of the introducing passage 8 and controls an intake quantity of the air or the mixture, and a pressure sensor 6, which detects a pressure inside the introducing passage 8 between the controlling valve 9 and the intake manifold 2.